The present invention relates to a control device of an engine connected with a stepped transmission via a clutch.
Conventionally, it is known to perform a so-called shift assist control so as to reduce a shock that occurs during a gear shift, namely a shift shock, in a vehicle having an engine connected with a stepped transmission via a clutch.
Specifically, in the gear shift, generally the stepped transmission is disconnected from the engine by the clutch, then the gear position is changed, and the stepped transmission is connected with the engine again. If the rotational speed of the stepped transmission is not synchronized with the speed of the engine when reconnecting, vibration (shift shock) occurs in the vehicle. For this reason, a control is performed to reduce the shift shock. For example, JPH09-068063A discloses such a control.
Specifically, JPH09-068063A discloses a control device for estimating, when the transmission is disconnected from the engine by the clutch, a gear position to be changed to when the gear shift has finished, based on a gear position immediately before the disconnection, and controlling a throttle valve to adjust the engine speed to the speed corresponding to the estimated gear position.
According to the device of JPH09-068063A, since the engine speed is controlled to the speed corresponding to the estimated gear position, a difference between the rotational speed of the transmission and the engine speed when they are reconnected can be small, reducing the shift shock.
However, since this device estimates the gear position to be changed to when the gear shift has finished, and maintains the engine speed at the speed corresponding to the estimated gear position, the engine speed may be maintained at a speed different from the vehicle operator's intention, causing discomfort to the vehicle operator. For example, in a case where the gear position which the vehicle operator inputs in the gear shift is different from the predicted gear position, or a case where the vehicle operator does not reconnect the transmission with the engine so as to stop the vehicle, the engine speed is maintained at a different value from the vehicle operator's intension. Therefore, a situation occurs where the vehicle operator feels uncomfortable.